Image reversal in manifold imaging

ABSTRACT

An imaging system wherein there is provided a manifold set comprising a cohesively weak imaging layer sandwiched between a donor sheet and a receiver sheet. An electrical potential is placed across the set and the imaging layer is exposed to extended imagewise activating electromagnetic radiation. The electrical potential across the set is then modified causing the image which conventionally adheres to the receiver sheet upon separation to adhere to thedonor sheet and the image which conventionally adheres to the donor sheet to adhere to the receiver sheet.

Unite States atent Krohn et a1.

[54] IMAGE REVERSAL IN MANIFOLD IMAGING [72]"1nventors: Ivar T. Krohn; Geoffrey A. Page; Gedeminas J. Reinis, all of Rochester,

[73} Assignee: Xerox Corporation, Stamford, Conn.

[22] Filed: Oct. 16, 1970 [21] Appl.No.: 81,357

Related U.S. Application Data [63] Continuation-impart of Ser. No. 609,058, Jan. 13,

1967, abandoned.

[52] U.S. Cl. ..96/l.3, 96/1 R, 117/175 [51] Int. Cl. 3g 13/22 [58] Field ofSearch ..96/1,1.3,1.4;117/17.5

[56] References Cited UNITED STATES PATENTS 2/1971 Clark ..96/1

[is] 3,655,372 Apr. 11, 1972 3,573,904 4/1971 Clark.. ..96/1

Primary Examiner-George F. Lesmes Assistant ExaminerJohn C. Cooper 111 Att0rney-James J. Ralabate, Donajames J. Ralabate, David C. Petre and Raymond C. Loyer 57] ABSTRACT An imaging system wherein there is provided a manifold set comprising a cohesively weak imaging layer sandwiched between a donor sheet and a receiver sheet. An electrical potential is placed across the set and the imaging layer is exposed to extended imagewise activating electromagnetic radiation. The electrical potential across the set is then modified causing the image which conventionally adheres to the receiver sheet upon separation to adhere to thedonor sheet and the image which conventionally adheres to the donor sheet to adhere to the receiver sheet.

' 23 Claims, 3 Drawing Figures IMAGE REVERSAL IN MANIFOLD IMAGING This application is a continuation-in-part of our copending application Ser. No. 609,058 filed Jan. 13, 1967, now abandoned.

BACKGROUND OF THE INVENTION The present invention relates in general to imaging and more specifically to a system for the formation of images by layer transfer in image configuration.

Although imaging techniques based on layer transfer of a colored material have been known in the past, these techniques have always been clumsy and difficult to operate because they depend upon photochemical reactions and generally involve the use of distinct layer materials for the two functions of imagewise transfer and image coloration. A typical example of the complex structures and sensitive materials employed in prior art techniques is described in US. Pat. No. 3,091,529 to Buskes. A more comprehensive discussion of prior art imaging techniques based on layer transfer may be found in copending application Ser. No. 452,641 filed May 3, 1965 in the U. S. Pat. Office, now abandoned.

Copending application Ser. No. 452,641 describes an imaging system utilizing a manifold set comprising a photoresponsive material between a pair of sheets. In this imaging system, an imageable plate is prepared by coating a layer of cohesively weak photoresponsive imaging material onto a substrate. This coated substrate is called the donor. When required the imaging layer is activated as by treating it with a solvent, swelling agent or partial solvent for the material, or by heating. This step may be eliminated, of course, if the layer retains sufficient residual solvent after having been coated on the substrate from a solution or paste. The activating step serves to weaken the imaging layer structurally so that it can be fractured more easily along a sharp line which defines the image to be reproduced. Once the imaging layer is activated, a receiving sheet is laid down over its surface. An electrical field is then applied across the imaging layer while it is exposed to a pattern of light and shadow representative of the image to be reproduced. Upon separation of the donor substrate or sheet and receiving sheet, the imaging layer fractures along the lines defined by the pattern of light and shadow to which the imaging layer has been exposed, with part of this layer being transferred to the receiving sheet while the remainder is retained on the donor sheet so that a positive image, that is, a duplicate of the original is produced on one sheet while a negative image is produced on the other.

At least one of the donor sheet and the receiver sheet is at least partially transparent to permit exposure of the imaging material to the image to be reproduced. The imaging layer serves the dual function of imparting light sensitivity to the system while at the same time acting as colorant for the final image produced. In one form the imaging layer comprises a photosensitive material such as metal-free phthalocyanine dispersed in a cohesively weak insulating binder. The best images are prepared by exposing the manifold set from the donor side of the imaging layer and accordingly, the donor substrate is normally transparent. In addition, the best images are obtained when the exposed portion of the imaging layer is caused to move to the receiver sheet. This means that in prior art systems high quality positive images were obtained only on transparent donor substrate materials. l-leretofore, it was not possible to obtain high quality positive images on an opaque material such as paper.

SUMMARY OF THE INVENTION It is another object of this invention to provide a system for layer transfer imaging which provides relatively high quality positive images on the receiver sheet.

It is another object of this invention to provide a system for layer transfer imaging which provides relatively high quality positive images on inexpensive opaque receiver materials.

It is another object of this invention to provide a layer transfer imaging system which provides relatively high quality images by transfer of the non-illuminated areas of the imaging layer.

It is another object of this invention to provide a system for layer transfer imaging wherein exposure through the donor layer results in relatively high quality positive images on the receiver sheet.

It is another object of this invention to provide a system for layer transfer imaging which provides a relatively high quality positive image on either donor or receiver sheet.

The above objects and others are accomplished in accordance with this invention by an imaging system utilizing a structure comprising a cohesively weak imaging layer sandwiched between a donor sheet and a receiving sheet hereinafterv referred to as a manifold set. In operation an electric field is placed across the imaging layer and the imaging layer is exposed to light projected from an image to be reproduced. After imaging the field across the imaging layer is modified by reversing the potential bias across the manifold set. That is, if the receiver sheet side was biased positive in respect to the donor side of the manifold sandwich prior to imaging, the receiver sheet side would be biased negative in respect to the donor side after imaging. The sheets are separated during or subsequent to application of the reverse bias.

It has been found that by reversing the field across the imaging layer the images obtained on the receiver sheet and donor sheet are also reversed. It is, thus, possible to provide a high quality positive image on opaque receiver materials.

Alternatively, the manifold sandwich may be charged by passing the sandwich between electrodes, imaging, then passing the sandwich between electrodes charged to the opposite polarity to effect reverse imaging.

The imaging layer may be exposed either through the donor sheet or the receiver sheet. Since exposure through the donor substrate allows the use of opaque receiver sheets, it is preferred to expose through the donor sheet. The light image may be formed by projecting light through a transparency or by projecting'light information from an opaque subject.

It has also been found that certain imaging layers respond to reverse biasing without exposure to activating electromagnetic radiation. That is, initially the imaging layer adheres more strongly to the donor sheet than to the receiving sheet; however, by charging the set by applying a field across the layer and then modifying the field across the layer, certain imaging layers are found to adhere more strongly to the receiver sheet than to the donor sheet. It is, therefore, possible to provide a system wherein the manifold set is given a uniform charge and then placed in an imagewise field of opposite polarity. Upon separation of the donor and receiver sheets, the imaging layer fractures in imagewise configuration providing a positive image on one of the sheets and a negative image on the other. For these imaging layers then, it is not necessary to provide photosensitive pigments dispersed in a binder, instead, pigments not considered photosensitive may be incorporated in the imaging layer. Typical of these pigments are carbon black, iron oxides, lead chromate in paste form designated alkyd paste, titanium dioxide, lead chromate and the various pigments used in printing inks and mixtures thereof.

In addition, it has been found that exposed imaging layers will reverse images when the manifold set is grounded before separation and imaging layers respond to a reduction in potential of the same polarity. That is, if the potential across the manifold set is reduced subsequent to imaging, those areas of the imaging layer which normally adhere to the receiver and donor sheets adhere instead to the donor and receiver sheets respectively.

The extent to which the potential must be reduced to achieve effective field reversal across the imaging layer varies mart H gan l. .Kn K

In most cases a reduction of the potential to a value below one-half to one-third of the original potential is sufficient to achieve image reversal.

In general, therefore, the steps of this invention are to activate and close the manifold set, establish an electric field across the imaging layer, expose the imaging layer to imagewise electromagnetic radiation, modify the electric field across the imaging layer and separating the receiver and donor sheets. By modifying then is meant that the electric field across the imaging layer is reversed by means of either reducing including grounding or reversing the potential across the Set.

The donor substrate and the receiving sheet may consist of any suitable insulating materials. Typical insulating materials are polyethylene, polyethylene terephthalate, cellulose acetate, paper, plastic coated paper, such as, polyethylene coated paper and mixtures thereof. Mylar, a polyester formed by the condensation reaction between ethylene glycol and terephthalic acid, available from E. I. DuPont de Nemours and Co., Inc, is preferred because of its physical strength and because it has good insulation qualities.

The basic physical property desired in the imaging layer is that it be frangible or structurally fracturable as prepared or after having been suitably activatedv That is, the layer must be sufficiently weak structurally so that the application of electrical field combined with the action of actinic radiation on the electrically photosensitive materials will fracture the imaging layer. Further, the layer must respond to the application of field the strength of which is below that field strength which will cause electrical breakdown or arcing across the imaging layer. Another term for cohesively weak, therefore, would be field fracturable."

Where the imaging layer is not sufficiently cohesively weak to allow imagewise fracture, it is desirable to include an activation step in the process of this invention. The activation step may take many forms such as heating the imaging layer thus reducing its cohesive strength or applying a substance to the surface of the imaging layer or including a substance in the imaging layer which substance lowers the cohesive strength of the layer or aids in lowering the cohesive strength. The substance so employed is termed an activator. Preferably, the activator should have a high resistivity so as to prevent electrical breakdown of the manifold sandwich. Accordingly, it will generally be found to be desirable to purify commercial grades of activators so as to remove impurities which might impart a higher level of conductivity. This may be accomplished by running the fluids through a clay column or by employing any other suitable purification technique. Generally speaking, the activator may consist of any suitable material having the aforementioned properties. For purposes of this specification and the appended claims, the term activator shall be understood to include not only materials which are conventionally termed solvents but also those which are partial solvents, swelling agents or softening agents for the imaging layer. The activator can be applied at any point in the process prior to separation of the manifold sandwich.

It is generally preferable that the activator have a relatively low boiling point so that fixing of the resulting image can be accomplished upon evaporation of the activator. If desired, fixing of the image can be accomplished more quickly with mild heating at most. It is to be understood, however, that the invention is not limited to the use of these relatively volatile activators. In fact, very high boiling point non-volatile activators including silicone oils such as dimethylpolysiloxanes and very high boiling point long chain aliphatic hydrocarbon oils ordinarily used as transformer oils such as Wemco-C transformer oil, available from Westinghouse Electric Co., have also been successfully utilized in the imaging process. Although these less volatile activators do not dry off by evaporation, image fixing can be accomplished contacting the final image with an absorbent sheet such as paper which absorbs the activator fluid. In short, any suitable volatile or nonvolatile activator may be employed. Typical activators include Sohio Odorless Solvent 3440, an aliphatic hydrocarbon fraction, available from Standard Oil Co. of Ohio, carbon tetrachloride, petroleum ether, Freon 2 l 4 (tetrafluorotetrachloropropane other halogenated hydrocarbons such as chloroform, methylene chloride, trichloroethylene, perchloroethylene, chlorobenzene, trichloromonofluoromethane, trichlorotrifluoroethane, trichlorotrifluoroethane, ethers such as diethyl ether, diisopropyl ether, dioxane, tetrahydrofuran, ethyleneglycol monoethyl ether, aromatic and aliphatic hydrocarbons such as benzene, toluene, xylene, hexane, cyclohexane, gasoline, mineral spirits and white mineral oil, vegetable oils such as coconut oil, babussu oil, palm oil, olive oil, castor oil, peanut oil and neatsfoot oil, decane, dodecane and mixtures thereof. Sohio Odorless Solvent 3440 is preferred because it is odorless, non-toxic and has a relatively high flash point.

Where imagewise activating electromagnetic radiation is used, the imaging layer may comprise any suitable photoresponsive material in a binder. Typical photoresponsive materials include photoconductors such as: substituted and unsubstituted phthalocyanine; quinacridones; zinc oxide; mercuric sulfide; Algol Yellow (C.I. No. 67,300); cadmium sulfide; cadmium selenide; lndofast brilliant scarlet (Cl. No, 71,140); zinc sulfide; selenium; antimony sulfide; mercuric oxide; indium trisulfide; titanium dioxide; arsenic sulfide; Pb 0 gallium triselenide; zine cadmium sulfide; lead iodide; lead selenide; lead sulfide; lead telluride; lead chromate; gallium telluride; mercuric selenide; and the iodides, sulfides, selenides and tellurides of bismuth, aluminum and molybdenum. Organic photoconductors, including those complexed with small amounts (up to about 5 percent) of suitable Lewis acids,

such as: 4,5-diphenylimidazolidinone; 4,5-diphenylimidazolidinethione; 4,5-bis-(4-amino-phenyl imidazolidinone; l ,S-cyanonaphthalene; l ,4- dicyanonaphthalene; aminophthalodinitrile; nitrophthalidinitrile; l ,2,5,6-tetraazacyclooctatetraene- (2,4,6,8); 3,4-di-(4-methoxy-phenyl)-7,8-diphenyl-l,2,5,6-

tetraazacyclooctatetraene-( 2,4,6,8 3 ,4-di-( 4-phenoxyphenyl-7,8-diphenyll ,2,5 ,6-tetraaza-cyclooctatetraene- (2,4,6,8 3,4,7,8-tetramethoxy-l ,2,5,6-tetraaze-cyclooctatetraene-(2,4,6,8); Z-mercaptobenzthiazole; 2-phenyl-4- diphenylidene-oxazolone; 2-phenyl-4-methoxy-benzylideneoxazolone; 6-hydroxy-2-phenyl-3-(p-dimethylamino phenyl)- benzofurane; 6-hydroxy2,3-di-(p-methoxyphenyl)-benzofurane; 6-hydroxy-2,3-di-(p-methoxyphenyl)-benzofurane; 2,3,5,6-tetra-(p-methoxyphenyl)-furo-(3,2f)-Benzofurane; 4- dimethylamino-benzylidene-benzhydrazide; 4- dimethylamino-benzylidene-isonicotinic acid hydrazide; furfurylidene-(2 )-2 '-dimethylaminobenzhydrazide; S-benzilidene-amino-acenaphthene; 3-benzylidene-amino-carbazole; (4'-N,N-dimethylamino-benzylidene)-p-N,N- dimethylaminoaniline; (2-nitro-benzylidene)-p-bromoaniline; N,N-dimethyl-N'-(2-nitro-4-cyano-benzylidene)-pphenylene-diamine; 2,4,-diphenyl-quinazoline; 2-(4-aminopheny])-4-phenyl-quinazoline; 2-phenyl-4-(4-di-methylamino-phenyl)-7-methoxy-quinazoline; l B-diphenyltetrahydroimidazole; l ,3-di-(4'-L -chlorophenyltetrahydroimidazole; l,3-diphenyl-2-4-dimethyl amino phenyl)-tetrahydroimidazole; 1,3-di-(p-tolyl)-2-[quinolyl-(2'-)]- tetrahydroimidazole; 3-( 4'-dimethylamino-phenyl)-5( 4' methoxyphenyl-6-phenyl-l ,2,4-triazone; 3-pyridil-(4)-5-(4- dimethylaminophenyl)z6-phenyl-l,2,4-triazine; 3,(4-aminophenyl)-5 ,o-diphenyl l ,2,4-triazine; 2,5-bis[4-amino-phenyll)]-l,3,4-triazole; 2,5-bis [4'-(l l-ethyl-N-acetyl-amino)- amino )-phenyl-( 1 1,3,4-triazole; 1,5-diphenyl-3-methylpyrazoline; l,3,4,S-tetraphenyl-pyrazoline; l-methyl-2-(34- dihydroxymethylene-phenyl)-benzimidazole; 2-(4- dimethylamino phenyl)-benzoxazole; 2(4-methoxyphenyl)- benzthiazole; 2,5-bis-[p-aminophenyl-( 1)]-l,3,4oxidiazole; 4,5-diphenyl-irnidazolone; 3,-aminocarbazole; copolymers and mixtures thereof. Any suitable Lewis acid (electron acceptor) may be employed under complexing conditions with many of the aforementioned more soluble organic materials and also with many of the more insoluble organics to impart very important increases in photosensitivity to those materials. Typical Lewis acids are 2,4,7-trinitro-9-fluorenone; 2,4,5,7- tetranitro-9-fluorenone; picric acid; 1,3,5-trinitro-benzene chloranil; benzo-quinone; 2,5-dichlorobenzoquinone; 2-6- dichlorobenzo-quinone; dichlorobenzo-quinone; chloranil; naphthoquinone-( 1,4); 2,3-dichloronaphthoquinone-( 1,4); anthraquinone; Z-methyl-anthraquinone; 1,4-dimethylanthraquinone; l-chloroanthraquinone; anthraquinone-2-carboxylic acid; l,5-dichloroanthraquinone, l-chloro-4- nitroanthraquinone; phenanthraene-quinone; acenaphthenequinone; pyranthrenequinone; chrysene-quinone; thionaphthenequinone; anthra-quinone-l,8-disulfonic acid and anthraquinone-Z-aldehyde; triphthaloyl-benzene-aldehydes such as bromal, 4-nitrobenzaldehyde; 2,6-di-chlorobenzaldehyde-Z. ethoxy-l-naphthaldehyde; anthracene-9-aldehyde; pyrene-B-aldehyde; oxindole-S-aldehyde; pyridine-2, o-dialdehyde, biphenyl-4-aldehyde; organic phosphonic acids such as 4-chloro-3-nitrobenZene-phosphonic acid; nitrophenols; such as 4-nitrophenol and picric acid; acid anhydrides; for example, acetic anhydride, succinic anhydride, maleic anhydride; phthalic anhydride, tetrachlorophthalic anhydride; perylene 3,4,9,lO-tetracarboxylic acid and chrysens- 2,3,8,9-tetracarboxylic anhydride; di-bromo maleic acid anhydride; metal halides of the metals and metalloids of the groups lB, II through to group VIII of the periodical system, for example; aluminum chloride, zinc chloride, ferric chloride tin tetrachloride, (stannic chloride); arsenic trichloride; stannous chloride; antimony pentachloride, magnesium chloride, magnesium bromide, calcium bromide, calcium iodide, strontium bromide, chromic bromide, manganous chloride, cobaltous chloride, cobaltic chloride, cupric bromide, ceric chloride, thorium chloride; arsenic tri-iodide; boron halide compounds, for example: boron trifluoride and boron trichloride; and ketones, such as acetophenone benzophenone; 2-acetyl-naphthalene; benzil; benzoin; 5- benzoyl acenaphthene, biacene-dione, 9-acetylanthracene, 9- benzoyl-anthracene; 4-(4-dimethylamino-cinnamoyl)-1- acetylbenzene; acetoacetic acid anilide; indandione( l,3),-('l- B-diketo-hydrindene); acenaphthene quinone-dichloride; anisil, 2,2-pyridil; furil; mineral acids such as the hydrogen halides, sulphuric acid and phosphoric acid; organic carboxylic acids; such as acetic acid and the substitution products thereof; monochloro-acetic acid; dichloro-acetic acid; trichloroacetic acid; phenylacetic acid; and o-methyl-coumarinylacetic acid (4); maleic acid, cinnamic acid; benzoic acid; 1-(4-diethyl-arnino-benzoyl)-benzene-2-carboxylic acid; phthalic acid; and tetrachlorophthalic acid; alpha-beta-dibrorno-beta-formyl-acrylic acid (mucobromic acid); dibromomaleic acid; Z-bromo-benzoic acid; gallic acid; 3-nitro-2- hydroxyl-l-benzoic acid; Z-nitro phenoxy-acetic acid, 2- nitrobenzoic acid; 3-nitrobenzoic acid; 4-nitrobenzoic acid; 3- nitro-4-ethoxy-benzoic acid; 2-chloro-4-nitro-l-benzoic acid, 2-chloro-4-nitro-l-benzoic acid, 3-nitro-4-methoxy-ben2oic acid, 4-nitro-l-methyl-ben2oic acid; 2-chloro-5-nitro-1- benzoic acid; 3-chloro-6-nitro-l-benzoic acid; 4-chloro-3- nitro-l-benzoic acid; 5-chloro-3-nitro2-hydroxy-benzoic acid; 4-chloro-2-hydroxybenzoic benzoic acid; 2,4-dinitro-lbenzoic acid; 2-bromo-5-nitrobenzoic acid; 4-chloro-phenylacetic acid; 2-chloro-cinnamic acid; 2-cyano-cinnamic acid;

2,4-dichlorobenzoic acid; 3,5-dinitrobenzoic acid; 3,5-dinitro salycylic acid; malonic acid; mucic acid; acetosalycylic acid; benzilic acid; butane-tetra-carboxylic acid; citric acid; cyanoacetic acid; cyclo-hexane-dicarboxylic acid; cycle-hexanecarboxylic acid; 9,10-dichloro-stearic acid; fumaric acid; itaconic acid; levulinic acid; (levulic acid); malic acid, succinic acid; alpha-bromo-stearic acid; citraconic acid; dibromo-succinic acid; pyrene-2,3,7,8-tetra-carboxylic acid; tartaric acid; organic sulphonic acid, such as 4-toluene sulphonic acid; and benzene sulphonic acid; 2,4-dinitro-lmethyl-benzene-6-sulphonic acid; 2,6-dinitro-l-hydroxybenzene-4-sulphonic acid and mixtures thereof.

In addition, other photoconductors may be formed by complexing one or more suitable Lewis acids with aromatic polymers which are ordinarily not thought of as photoconductors. Typical aromatic polymers include the following illustrative materials: polyamides, polyimides, polycarbonates, epoxy resins, phenoxy resins, aromatic silicone resins, polyphenylene oxide, polysulfones, melamine resins, phenolic resins and mixtures and copolymers thereof where applicable.

Phthalocyanines are preferred because of their high sensitivity and excellent color. Of the phthalocyanines alpha and x forms of metal free phthalocyanine have given optimum results. However, any other suitable phthalocyanine may be used where desired. Any suitable phthalocyanine may be used to prepare the photoconductive layer of the present invention. The phthalocyanine used may be in any suitable crystal form. It may be substituted or unsubstituted both in the ring and straight chain portions. Reference is made to a book entitled Phthalocyanine Compounds" by F. H. Moser and A. L. Thomas, published by the Reinhold Publishing Company, 1963 edition for a detailed description of phthalocyanines and their synthesis. Any suitable phthalocyanine may be used in the present invention. Phthalocyanines emcompassed within this invention may be described as compositions having four isoindole groups linked by four nitrogen atoms in such a manner so as to form a conjugated chain, said compositions have the general formula (C i-L,N ),R, wherein R is selected from the group consisting of hydrogen, deuterium, lithium, sodium, potassium, copper, silver, beryllium, magnesium, calcium, zinc, cadmium, barium, mercury, aluminum, gallium, indium, lanthanum, neodymium, samarium, europium, gadolinium, dysprosium, holium, erbium, thylium, ytterbium, lutecium, titanium, tin, hafnium, lead, silicon, germanium, thorium, vanadium, antimony, chromium, molybdenum, uranium, manganese, iron, cobalt, nickel, rhodium, palladium, osmium and platinum; and n is a value of greater than 0 and equal to or less than 2. Any other suitable phthalocyanines such as ring or aliphatically substituted metallic and/or nonmetallic phthalocyanines may also be used if suitable. Typical phthalocyanines are: aluminum phthalocyanine, aluminum polychlorophthalocyanine, antimony phthalocyanine, barium phthalocyanine, beryllium phthalocyanine, cadmium hexadecachlorophthalocyanine, cadmium phthalocyanine, calcium phthalocyanine, cerium phthalocyanine, chromium phthalocyanine, cobalt phthalocyanine, cobalt chlorophthalocyanine, copper 4-aminophthalocyanine, copper bromochlorophthalocyanine, copper 4-chlorophthalocyanine, copper 4-nitrophthalocyanine, copper phthalocyanine, copper phthalocyanine sulfonate, copper polychlorophthalocyanine, deuterio-phthalocyanine, dysprosium phthalocyanine, erbium phthalocyanine, europium phthalocyanine, gadolinium phthalocyanine, gallium phthalocyanine, germanium phthalocyanine, hafnium phthalocyanine, halogen substituted phthalocyanine, holmium phthalocyanine, indium phthalocyanine, iron phthalocyanine, iron polyhalophthalocyanine, lanthanum phthalocyanine, lead phthalocyanine, lead polychlorophthalocyanine, cobalt hexaphenylphthalocyanine, copper pentaphenyl-phthalocyanine, lithium phthalocyanine, lutecium phthalocyanine, magnesium phthalocyanine, manganese phthalocyanine, mercury phthalocyanine, molybdenum phthalocyanine, naphthalocyanine, neodymium phthalocyanine, nickel phthalocyanine,

nickel polyhalophthalocyanine, osmium phthalocyanine, palladium phthalocyanine, palladium chlorophthalocyanine, alkoxyphthalocyanine, alkylaminophthalocyanine, alkylmercaptophthalocyanine, arlkyl-arninophthalocyanine, aryloxyphthalocyanine, arylmercaptophthalocyanine, copper phthalocyanine piperidine, cycloalkylaminophthalocyanine, dialkylaminophthalocyanine, diaralkylaminophthalocyanine, dicycloalkylaminophthalocyanine, hexadecaphydrophthalocyanine, imidomethylphthalocyanine, 1,2 naphthalocyanine, 2,3 naphthalocyanine, octaazaphthalocyanine, sulfur phthalocyanine tetraazaphthalocyanine, tetra-4-acetylaminophthalocyanine, tetra-4-aminobenzoylphthalocyanine, tetra-4- aminophthalocyanine, tetrachloromethylphthalocyanine, tetradiazo-phthalocyanine, tetra-4,4-dimethyloctaazaphthalocyanine, tetra-4, S-diphenylenedioxide phthalocyanine, tetra- 4,5-diphenyl-octaazaphthalocyanine, tetra-( 6-methylbenzothiazoyl) phthalocyanine, tetra-p-methylphenylaminophthalocyanine, tetramethyl-phthalocyanine, tetranaphtho-triazolylphthalocyanine, tetra-4-naphthylphthalocyanine, tetra-4-nitrophthalocyanine, tetra-perinaphthylene- 4,5-octa-azaphthalocyanine, tetra-2,3-phenyleneoxide phthalocyanine, tetra-4-phenyl-octaazaphthalocyanine, tetraphenylphthalocyanine, tetraphenylphthalocyanine tetracarboxylic acid, tetraphenylphthalocyanine tetraban'um carboxylate, tetraphenylphthalocyanine tetra-calcium carbox ylate, tetrapyridyphthalocyanine, tetra-4-trifluoromethylmercaptophthalocyanine, tetra-4-trifluoromethylphthalocyanine, 4,5thionaphthene-octaazaphthalocyanine, platinum phthalocyanine, potassium phthalocyanine, rhodium phthalocyanine, samarium phthalocyanine, silver phthalocyanine, silicone phthalocyanine, sodium phthalocyanine, sulfonated phthalocyanine, thorium phthalocyanine, thulium phthalocyanine, tin chlorophthalocyanine, tin phthalocyanine, titanium phthalocyanine, uranium phthalocyanine, vanadium phthalocyanine, ytterbium phthalocyanine, zinc chlorophthalocyanine, zinc phthalocyanine, others described in the Moser test and mixtures, dimers, trimers, oligomers polymers, copolymers or mixtures thereof.

lt is also to be understood in connection with the heterogeneous system, that the photoconductive particles themselves may consist of any suitable one or more of the aforementioned photoconductors, either organic or inorganic, dispersed in, in solid solution in, or copolymerized with, any suitable insulating resin whether or not the resin itself is photoconductive. This particular type of particle may be particularly desirable to facilitate dispersion of the particle, to prevent undesirable reactions between the binder and the photoconductor or between the photoconductor and the activator and for similar purposes. Typical resins include polyethylene, polypropylene, polyamides, polymethacrylates, polyacrylates, polyvinyl chlorides, polyvinyl acetates, polystyrene, polysiloxanes, chlorinated rubbers, polyacrylonitrile, epoxies, phenolics, hydrocarbon resins and other natural resins such as rosin derivatives as well as mixtures and copolymers thereof. Polyethylene is preferred because of its low melting point and because it is readily available.

The binder material in the heterogeneous imaging layer or the material used in conjunction with the electrically photosensitive materials in the homogeneous layer, where applicable, may comprise any suitable cohesively weak insulating material or material which can be rendered cohesively weak. Typical materials include: microcrystalline waxes such as: Sunoco 1290, Sunoco 5825, Sunoco 985, all available from Sun Oil Co.; Paraflint RG, available from the Moore and Munger Company; paraffin waxes such as: Sunoco 5512, Sunoco 3425, available from Sun Oil Co.; Sohio Parowax, available from Standard Oil of Ohio, waxes made from hydrogenated oils such as: Capitol City 1380 wax, available from Capitol City Products, Co. Columbus, Ohio; Caster Wax L-2790, available from Baker Caster Oil Co.; Vitikote L-304, available from Duro Commodities; polyethylenes such as: Eastman Epolene N-ll, Eastman Epolene C-l2, available from Eastman Chemical Products, Co.; Polyethylene DYJT, Polyethylene DYLT, Polyethylene DYDT, all available from Union Carbide Corp.; Marlex TR 822, Marlex 1478, available from Phillips Petroleum Co.; Epolene C-l3, Eoplene C-lO, available from Eastman Chemical Products, Co.; Polyethylene AC8, Polyethylene AC6l2, Polyethylene AC324, available from Allied Chemicals; modified styrenes such as: Piccotex 75, Piccotex lOO, Piccotex 120, available from Pennsylvania Industrial Chemical; Vinylacetate-ethylene copolymers such as: Elvax Resin 210, Elvax Resin 310, Elvax Resin 420, available from E. I. DuPont de Nemours & Co., Inc.; Vistanex MH, Vistanex L-80, available from Enjay Chemical Co.; vinyl chloride-vinyl acetate copolymers such as: Vinylite VYLF, available from Union Carbide Corp.; styrene-vinyl toluene copolymers; polypropylenes; and mixtures thereof. The use of an insulating binder is preferred because it allows the use of a larger range of electrical field strength.

As stated above, according to the process of this invention, the imaging layer is subjected to an electrical field. The electrical field can be applied in many ways. Generally, the sandwich is placed between electrodes having different electrical potential. Also, an electrical charge can be imposed upon one or both of the donor sheet and receiver sheet before or after forming the sandwich by any one of several known methods for inducing a static electrical charge into a material. Static charges can be imposed by contacting the sheet or substrate with an electrically charged electrode. Alternatively, one or both sheets may be charged using corona discharge devices such as those described in US. Pat. Nos. 2,588,699 to Carlson, US. Pat. No. 2,777,957 to Walkup, US. Pat. No. 2,885,556 to Gundlach or by using conductive rollers as described in US. Pat. No. 2,980,834 to Tregay et al., or by frictional means as described in US. Pat. No. 2,297,691 to Carlson or other suitable apparatus.

Thus, the electrical field can be provided by means known to the art for subjecting an area to an electrical field. The electrodes employed may comprise any suitable conductive material and may be flexible or rigid. Typical conductive materials include: metals such as aluminum, brass, steel, copper, nickel, zinc, etc., metallic coatings on plastic substrates rubber rendered conductive by the inclusion of a suitable material therein or paper rendered conductive by the inclusion of a suitable material therein or through conditioning in a humid atmosphere to insure the presence therein of sufficient water content to render the material conductive. Conductive rubber is preferred because of its flexibility. In the process of this invention wherein the imaging layer is exposed to activating electromagnetic radiation while positioned between electrodes one of the electrodes must be at least partially transparent. The transparent conductive electrode may be made of any suitable conductive transparent material and may be flexible or rigid. Typical conductive transparent materials include cellophane, conductively coated glass, such as tin or indium oxide coated glass, aluminum coated glass or similar coatings on plastic substrates. NESA, a tin oxide coated glass available from Pittsburgh Plate Glass Co., is preferred because it is a good conductor and is highly transparent and is readily available. In the process of this invention wherein the donor and/or receiver is composed of conductive material each may also be employed as the electrodes by which the imaging layer is subjected to an electrical field. That is either when employed as an electrode one or both of the donor sheet and receiver sheet may serve a dual function in the process of this invention.

The original strength of the electrical potential applied across the manifold set depends on the structure of the manifold set and the materials used. For example, if highly insulating receiver and donor substrate materials are used, a much higher potential may be applied than if relatively conductive donor and receiver sheets are used. The potential strength required may, however, be easily determined. If too large a potential is applied, electrical breakdown of the manifold sandwich will occur allowing arcing between the electrodes. If too little potential is applied, the imaging layer will not fracture in imagewise configuration. By way of example, if a 3 mil Mylar receiver sheet and a 2 mil Mylar donor sheet are used, potentials as high as 20,000 volts may be applied between the electrodes. The preferred potentials across the manifold sandwich are, however, in the range of from about 3,000 volts per mil to about 7,000 volts per mil of electrically insulating material. Since relatively high potentials are utilized, it is desirable to insert a resistor in the circuit to limit the flow of current. Resistors on the order of from about 1 megohm to about 20,000 megohms are conventionally used.

The advantages of this improved method of imaging will become apparent upon consideration of the detailed disclosure of the invention especially when taken in conjunction with accompanying drawings wherein:

FIG. 1 is a side sectional view of a photosensitive imaging member for use in the invention.

FIG. 2 is a side sectional view diagrammatically illustrating the final process step of this invention.

FIG. 3 is a curve showing the effect of reverse biasing on the amount of the exposed imaging layer which adheres to the receiver sheet upon separation of the donor and receiver sheets.

Referring now to FIG. 1, imaging layer 2, comprising photosensitive particles 4 dispersed in binder 3, is deposited on an insulating donor substrate sheet 5. The image receiving portion of the manifold set comprises an insulating receiver sheet 6. Either or both of sheets 5 and 6 may be transparent so as to permit exposure of imaging layer 2. The embodiment of the invention shown in FIG. 1 is preferred because it allows for the use of inexpensive high strength insulating material as donor substrate sheet 5 and receiver sheet 6.

Referring now to FIG. 2, the first step illustrated in the imaging process is the activation step. In this stage of the imaging process, the manifold set is open and the activator is supplied to imaging layer 12 or to receiver sheet 16 following which these layers are placed together. Although the activator may be applied by any suitable technique such as with a brush, with a smooth or rough surfaced roller, by flow coating, by vapor condensation or the like, FIG. 2 which diagrammatically illustrates the process steps of this invention shows the activator fluid 23 being sprayed onto imaging layer 12 of the manifold set from a container 24. Following the deposition of this activator fluid, the set is closed by a roller 26 which also serves to squeeze out any excess activator fluid which may have been deposited. The activator serves to swell or otherwise weaken and thereby lower the cohesive strength of imaging layer 12. In certain instances the first two steps of the imaging process as diagrammatically illustrated in FIG. 2 may be omitted; thus, for example, a manifold set which is preactivated during manufacture may be supplied wherein imaging layer 12 is initially fabricated to have a low enough cohesive strength so that activation may be omitted and receiving layer 16 may be adhered to the surface of imaging layer 12 at the time when that layer is coated on substrate 17 either from solution or from a hot melt. It is generally preferable, however, to include an activation step in the process because stronger and more permanent imaging layers may then be provided which can withstand storage and transportation prior to imaging. Once the proper physical properties have been imparted to imaging layer 12 and the receiving sheet 16 has been placed on layer 12, an electrical field is applied across the manifold set through electrodes 18 and 21 which are connected to potential source 28 and resistor 30. Alternatively, either or both of the donor sheet and the receiver sheet may be charged prior to their being placed together in the sandwich.

The manifold set is then placed on transparent plate 27 where it is exposed to light image 29. Light image 29 may be light projected through a transparency or light information projected from an opaque subject. In a continuous operation,

the light image preferably is projected through a slit so thatthere is little or no relative movement between the projected image and the manifold sandwich during the exposure. A second electrical field is then applied across the manifold set through electrodes 19 and 22 which are connected to potential source 31 and resistor 33. As shown the original charging is accomplished with receiver side electrode 18 biased positive with respect to donor side electrode 21. The reverse biasing is accomplished by having receiver side electrode 19 biased negative in respect to donor side electrode 22. Some imaging layers, however, provide better quality images when electrode 18 is biased negative and electrode 21 is biased positive. Reverse biasing would then be accomplished by biasing electrode 19 positive and electrode 22 negative. In addition, certain donor layers have been found to reverse images if the manifold set is grounded between imaging and separation, therefore, electrodes 19 and 22 may be grounded instead of being connected to a source of potential.

Although FIG. 2 is intended to represent the use of thin rods as electrodes 18, 21, 19 and 22, these electrodes may be conductive rollers, brushes, edges of conductive objects, strips of conductive material, wire or other suitable charging device. In addition, charging may be accomplished by the use of corona discharge on one or both sides of the manifold set.

Although FIG. 2 shows the manifold set contacting electrodes 21 and 22 only, electrodes 18 and 19 may also contact the surface of the set. However, where thin rods are used it is preferable to leave a small space between electrodes 18 and 19 and the manifold sandwich to prevent binding.

The sandwich then passes under roller 32 which acts as a guide and as a bearing point for the separation. Upon separation of substrate 17 and receiving sheet 16, imaging layer 12 fractures along the edges of exposed areas and at the surface where it had adhered to substrate 17. Accordingly, once separation is complete, exposed portions of imaging layer 12 are retained on one of layers 17 and 16 while the substantially unexposed portions are retained on the other layer.

Referring now to FIG. 3, curves 30 and 40 approximately represent results obtained when using the layers and apparatus of Example 1. Curve 30 approximates the results obtained without reversal biasing, curve 40 approximates the results obtained with reversal biasing.

Point 31 on curve 30 shows that with the receiver side biased positive and with a total exposure of 0.4 foot-candleseconds, substantially none of the imaging layer adheres to the receiver sheet upon separation of the donor and receiver sheets. Point 41 on curve 40 shows that if after charging the manifold sandwich with the receiver side biased positive, exposing the manifold set to a total exposure of 0.4 foot-candleseconds and then biasing the receiver side negative that substantially all of the exposed imaging layer adheres to the receiver sheet.

Point 32 on Curve 30 shows that with the receiver sheet biased positive imagewise exposure of 2.0 foot-candle-seconds results in substantially all of the exposed area adhering to the receiver sheets.

Point 42 on curve 40 shows that after charging the manifold set with the receiver sheet biased positive, exposing the manifold set to a total exposure of 2.0 foot-candle-seconds and then biasing the receiver sheet negative, that substantially none of the imaging layer adheres to the receiver sheet upon separation of the donor and receiver sheets.

It should be pointed out that with the imaging layer of Example I at some point below 0.1 foot-candle-seconds reversal biasing does not cause the imaging layer to adhere to the receiver sheet. This is not true for the imaging layer of Example IV, which will transfer without any exposure after the initial charging.

The following examples further specifically illustrate the present invention. The examples below are intended to illustrate various preferred embodiments of the improved imaging method.'The parts and percentages are by weight unless otherwise indicated.

EXAMPLE I A commercial metal-free phthalocyanine is first purified by odichlorobenzene extraction to remove organic impurities. Since this extraction step yields the less sensitive beta crystalline form, the desired X form is obtained by dissolving about 100 grams of beta in approximately 600 cc. of sulfuric acid precipitating it by pouring the solution into about 3,000 cc. of ice water and washing with water to neutrality. The thus purified alpha phthalocyanine is then salt milled for 6 days and desalted by slurrying in distilled water, vacuum filtering, water washing and finally methanol washing until the initial filtrate is clear. After vacuum drying to remove residual methanol, the X" form phthalocyanine thus produced is used to prepare the imaging layer according to the following procedure: About grams of the X" form phthalocyanine is added to about 5 grams of Algol Yellow GC, l,2,5,6-di-(C,C'-diphenyl)thiazole-anthraquinone, C.l. No. 67300, available from General Dyestuffs and about 2.8 grams of purified Watchung Red B, l-(4'-methyl-5-chloroazobenzene-2'-sulfonic acid)-2- hydroxy-3-naphthoic acid, C.l. No. 15865, available from E. l. DuPont de Nemours & Co. which is purified as follows: Approximately 240 grams of the Watchung Red B is slurried in about 2,400 milliliters of Sohio Odorless Solvent 3440, a mixture of kerosene fractions available from the Standard Oil Company of Ohio. The slurry is then heated to a temperature of about 65 C. and held there for about one-half hour. The slurry is then filtered through a glass sintered filter. The solids are then reslurried with petroleum ether (90 to 120 C.) available from Matheson Coleman and Bell Division of the Matheson Company, East Rutherford, New Jersey and filtered through a glass sintered filter. The solids are then dried in an oven at about 50 C.

About 8 grams of Sunoco Microcrystalline Wax Grade 5825 having an ASTM-D-l27 melting point of 151 F. available from Sunoco and about 2 grams Paraflint R. G., a low molecular weight paraffinic material available from the Moore & Munger Company, New York City and about 320 milliliters of petroleum ether (90 to 120 C.) and about 40 milliliters of Sohio Odorless Solvent 3440 are placed with the pigments in a glass jar containing /2 inch flint pebbles. The mixture is then milled by revolving the glass jar at about 70 r.p.m. for about 16 hours. The mixture is then heated for approximately 2 hours at about 45 C. and allowed to cool to room temperature. The mixture is then ready for coating on the donor substrate. The paste-like mixture is then coated in subdued green light on 1 mil Mylar (a polyester formed by the condensation reaction between ethylene glycol and terephthalic acid available from E. l. DuPont de Nemours & Co., Inc. with a No. 36 wire wound drawdown to produce a coating thickness when dried of approximately 7 /2 microns. The coating and one mil Mylar sheet is then dried in the dark at a temperature of about 33 C. for one-half hour. The coated donor is then placed on the tin oxide surface of a ,4; inch NESA glass plate with its coating facing away from the tin oxide. A receiver sheet also of 1 mil Mylar is placed over the donor. A sheet of black electrically conductive paper available as Grade 505 black photographic paper from Knowlton Paper Company, Watertown, New York is placed over the receiver sheet to form the complete manifold set. The receiver sheet is then lifted up and the imaging layer activated with one brush stroke of a wide camels hair brush saturated with Sohio 3440. The receiver sheet is then lowered back down and a roller is rolled slowly once over the closed manifold set with light pressure to remove excess solvent. The negative terminal of a 9,000 volt DC power supply is then connected to the NESA coating in series with a 5,500 megohm resistor and the positive terminal is connected to the black opaque electrode and grounded. With the voltage applied, a white incandescent light image is projected through the NESA glass using a 300 watt Bell and Howell Headliner Model 708 Duo Slide Projector having a piece of Trans-Positive sheet (Frosted) available from Xerox,

Rochester, New York and a variable aperture placed in front of it. The distance from the projector to the imaging donor layer is approximately 60 inches. The light incident on the imaging layer is approximately 2 foot-candles. The imagewise exposure is continued for about 1.0 seconds resulting in an application of total incident energy on the imaging layer of about 2.0 foot-candle-seconds. After exposure the positive terminal of the above mentioned 9,000 volt power supply is then connected to the NESA coating and the negative terminal is connected to the black opaque electrode and grounded. Potential is applied for about 10 seconds. After reverse biasing, the receiver sheet is peeled from the set with the potential source still connected. The small amount of Sohio present evaporates after separation of the sheets yeilding a pair of excellent quality images with a positive image adhering to the receiver sheet and a negative image on the donor sheet.

EXAMPLE I] PRIOR ART The experiment of Example I is repeated except that immediately after imagewise exposure and prior to reversing the field across the imaging layer the receiver sheet is peeled from the set with the potential source still connected. Upon separation of the sheets, a pair of high quality images are observed with the positive image adhering to the donor sheet and a negative image adhering to the receiver sheet.

EXAMPLE III The manifold set of Example I is activated as in Example I. The receiver sheet is then lowered back down and a roller is rolled slowly once over the closed manifold set with light pressure to remove excess solvent. Two electrodes consisting of $41 inch diameter copper rods 3 inches long are placed in spaced relationship one above the other at a distance of about 6 mils. The upper electrode is connected to the positive terminal of a 9,000 volt DC power supply and grounded. The lower electrode is then connected to the negative terminal of the power supply. The following steps are performed under safe light conditions. The manifold sandwich is drawn with the receiver side up through the space between the two electrodes while a potential is applied between the electrodes. To prevent arcing the manifold sandwich width provided is about one-half inch wider than the electrodes are long. For example, if approximately 3 inch electrodes are used, a manifold sandwich of about 3 /& inches width is used. The inch overlap on each end of the electrodes prevents sparking between the two electrodes. The charged manifold sandwich is then placed on a glass plate. A white incandescent light image is then projected through the glass plate using the light source of Example I. The distance from the projector to the imaging donor layer is approximately 60 inches. The light incident on the imaging layer is adjusted to approximately 2 foot-candles. Imagewise exposure is continued for 2 seconds resulting in application of incident energy on the manifold set of about i foot-candlesecond. The manifold set is then passed receiver side up between the electrodes above mentioned with the upper electrode this time connected to the negative terminal of the 9,000 volt DC power supply and the lower electrode connected to the positive terminal of the power supply. The receiver sheet is then peeled from the set yielding a pair of excellent quality images with a positive image adhering to the receiver sheet and a negative image adhering to the donor sheet.

EXAMPLE IV The experiment of Example III is repeated except that the 1 mil Mylar receiver sheet is replaced by a sheet of 2 mil thick paper. Upon separation of the sheets, a high quality positive image is observed adhering to the receiver sheet and a high quality negative image is observed adhering to the donor sheet.

About 2 1; grams of the X form of phthalocyanine prepared as in Example I, about 1.2 grams of Algol Yellow and about 2.8 grams of Irgazine Red available from the Geigy Chemical Company are added to about 60 milliliters of petroleum ether, 90-l20 C., and milled as in Example I for about 16 hours. The mixture is then added to a binder prepared as follows:

About 1 mol of alpha methyl styrene and about 1 mol of vinyl toluene are added to sufiicient xylene to produce a 40 percent solution. A catalytic amount of boron trifluoride etherate is then added and the mixture stirred until polymerization is complete. After polymerization, sufficient methanol is added to decompose any boron trifluoride present, the polymer is then isolated by steam distillation. The resulting polymer is available as Piccotex 100 from the Pennsylvania Industrial Chemical Company.

About 2 V2 grams of the Piccotex 100 is added to about 3 grams of polyethylene DYLT available from the Union Carbide Company, and about 1 V2 grams of Paraflint R. G. and about one-half gram of Elvax 420, an ethylene-vinyl-acetate copolymer available from the E. I. DuPont de Nemours & Company. The mixture is then dissolved in about 20 milliliters of Sohio 3440 at about the boiling point. The solution is then allowed to cool to room temperature. The solution is then added to the mixture of pigments and milled as in Example I for about 16 hours. The mixture is heated to a temperature of approximately 65 C. for approximately 2 hours. It is then allowed to cool to approximately room temperature. About 60 milliliters of reagent grade isopropanol is then added to the mixture and milled for about another minutes. The paste is then ready for coating on a donor substrate. The paste is then coated in subdued green light on 2 mil Mylar with a No. 36 wire wound drawdown rod to produce a coating thickness dry of about 7 microns. The donor is then dried in the dark at a temperature of about 33 C. for about 30 minutes. The coated donor is then placed on the tin oxide surface of a NESA glass plate with its coating facing away from the tin oxide. A receiver sheet of 2 mil thick bond paper is placed over the donor layer. Then, a sheet of the black electrically conductive paper of Example I is placed over the receiver sheet to form the complete manifold set. The receiver sheet is then lifted up and the imaging layer activated with one quick brush stroke of a wide camels hair brush saturated with Sohio 3440. The receiver sheet is then lowered back down and a roller is rolled slowly once over the closed manifold set with light pressure to remove excess Sohio. The negative terminal of 9,000 volt DC power supply is then connected to the NESA coating in series with a 5,500 megohm resistor and the positive terminal is connected to the black opaque electrode and grounded. With the voltage applied, an image is projected onto the imaging layer as in Example I. The imagewise exposure is continued for about 0.7 seconds resulting in the application of a total incident energy of about 0.7 foot-candle-seconds on the imaging layer. After exposure the power supply is disconnected and the manifold set is subjected to a reversing potential applied by connecting the positive terminal of a 5,000 volt DC power supply to the NESA coating and connecting the negative terminal to the black opaque electrode and ground. The reversing potential is applied for approximately 10 seconds. The receiver sheet is then peeled from the set with the potential still applied yielding a pair of high quality images with the positive image adhering to the receiver sheet and a negative image adhering to the donor sheet.

EXAMPLE VI The experiment of Example III is repeated except that the manifold set of Example V is used and the reversing set. of electrodes are connected to a 2,000 volt power supply. The receiver sheet is stripped from the manifold set yielding a pair of high quality images with the positive image adhering to the receiver sheet and a negative image adhering to the donor sheet.

EXAMPLE VII The experiment of Example V is repeated with the exception that there is no imagewise exposure. The receiver sheet is stripped from the manifoldset. Substantially all of the imaging layer is found adhering to the receiver sheet.

EXAMPLE VIII The experiment of Example V is repeated except that the NESA glass electrode is replaced by an image shaped conductive electrode and no imagewise exposure is used. The receiver sheet is peeled from the set yielding a high quality pair of images with the positive image adhering to the receiver sheet and a negative image adhering to the donor sheet.

EXAMPLE IX About 6.4 grams of the X form phthalocyanine prepared as in Example I, about 6.4 grams of Algol Yellow, about 8.0 grams of Sunoco Wax 5825, about 2.0 grams Paraflint R. 6., about 180 cc. of isopropanol, about 40 cc. Sohio 3440, and about 140 cc. petroleum ether (l20 C.) are milled as in Example I for about 16 hours. The mixture is then heated to a temperature of about 45 C. and held at that temperature for 2 /2 hours. The mixture is then allowed to cool for one-half hour and then milled for 1 hour.

The paste-like mixture is then coated on 2 mil Mylar as in Example I and dried in the dark at a temperature of about 33 C. for about one-half hour. The imaging layer is then activated with one brush stroke of a wide camels hair brush saturated with Sohio 3440. A receiver sheet of 1 mil Mylar is then placed over the activated imaging layer forming the completed manifold set. The manifold sandwich is then charged under safelight as in Example III except that the upper electrode is connected to the negative terminal of a power supply of 9,700 volts DC. The imaging layer is then exposed as in Example III except that the imagewise exposure is approximately 0.48 seconds resulting in a total incident energy of about 0.48 foot-candle-seconds. The manifold sandwich is then passed between two grounded 1 inch diameter aluminum rollers. The rollers are in contact with both surfaces of the manifold sandwich. The receiver sheet is then peeled from the set yielding a pair of images with a positive image adhering to the receiver sheet and a negative image adhering to the donor sheet.

EXAMPLE X The experiment of Example IX is repeated except that the 1 mil Mylar receiver sheet is replaced by a sheet of 2 mil paper. Upon separation of the sheets, a positive imaging adheres to the paper receiver sheet and a negative image adheres to the donor sheet.

EXAMPLE XI About 6.4 grams of the X form phthalocyanine prepared as in Example I, about 6.4 grams of Algol Yellow, about 8 grams of Sunoco Wax 5825, about 2 grams of Paraflint R. III with about 60 ml. ethanol and about 360 ml. of petroleum ether (90l20 C.) are milled as in Example I for 16 hours. The paste-like mixture is then coated on a 2 mil Mylar sheet as in Example I and dried in the dark at a temperature of about 33 C. for one-half hour. The imaging layer is then activated with one brush stroke of a wide camels hair brush saturated with Sohio 3440. A receiver sheet of 1 mil Mylar is then placed over the activated imaging layer forming the completed manifold sandwich. The manifold set is then charged as in Example III except that the upper electrode is connected to the negative terminal of a potential source of 8,000 volts DC. The imaging layer is then exposed to an image as in Example III except that the exposure is continued for about 0.85 seconds resulting in a total exposure of 0.85 footcandle-seconds. The manifold set is then passed receiver side up between the electrodes as in Example III with the upper electrode connected to the positive terminal of a bold 1,000

light volt DC power supply and the lower electrode connected to the negative terminal. The receiver sheet is then peeled from the set yielding a pair of images with a positive image adhering to the receiver sheet and a negative image adhering to the donor sheet.

EXAMPLE XII The experiment of Example X1 is repeated except that after imagewise exposure the manifold set is passed receiver side up between the electrodes of Example 11] with the upper electrode connected to the negative terminal of the power supply of Example X! and the lower electrode connected to the positive terminal of the power supply and grounded. The receiver sheet is then peeled from the set yielding a pair of good quality images with a positive image adhering to the receiver sheet and a negative image adhering to the donor sheet.

EXAMPLE XII] The experiment of Example X1 is repeated except that after imagewise exposure the manifold set is passed receiver side up between the electrodes of Example ill with the upper electrode connected to the negative terminal of a bold 4,000 light volt DC power supply and the lower electrode connected to the positive terminal and grounded. The receiver sheet is then peeled from the set yielding a pair of excellent quality images with a positive image adhering to the receiver sheet and a negative image adhering to the donor sheet.

Although specific components and proportions have been stated in the above description of preferred embodiments of the invention, other typical materials as listed above if suitable may be used with similar results. In addition, other materials may be added to the mixture to synergize, enhance or otherwise modify the properties of the imaging layer. For example, various dyes, spectral sensitizers or electrical sensitizers such as Lewis acids may be added to the several layers.

Other modifications and ramifications of the present invention will occur to those skilled in the art upon a reading of the present disclosure. These are intended to be included within the scope of this invention.

What is claimed is:

1. A method of imaging comprising:

a. providing a manifold set comprising an electrically photosensitive imaging layer sandwiched between a donor sheet and a receiving sheet, said layer being structurally fracturable in response to the combined effect of an applied electrical field and exposure to electromagnetic radiation to which said layer is sensitive, at least one of said donor and receiver sheet being at least partially transparent to said electromagnetic radiation;

b. maintaining an electric field across said imaging layer by means of a potential across said set;

c. exposing said imaging layer to a pattern of activating electromagnetic radiation;

d. modifying said electric field across said imaging layer wherein said modification involves reducing, grounding or reversing the potential across said manifold set; and

e. separating said receiver sheet from said donor sheet whereby said imaging layer fractures in imagewise configuration forming a positive image conforming to the original on one of said receiver and donor sheets and negative image on the other of said receiver and donor sheets and whereby the location of said images with respect to said donor and receiver sheets are reversed from those obtained in the above process in the absence of step (d).

2. The method of claim 1 wherein said modification comprises reducing said potential to a value less than one-third of the original potential, said modified potential being of the same polarity as said original potential.

3. The method of claim 1 wherein said modification comprises grounding the potential across said manifold set.

4. The method of claim 1 wherein said modification comprises reversing the polarity of said potential across said manifold set.

5. The method of claim 1 wherein said donor sheet is at least partially transparent and said imaging layer is exposed through said donor sheet.

6. The method of claim 1 wherein said receiver sheet is at least partially transparent and said imaging layer is exposed through said receiver sheet.

7. The method of claim 1 further including the step of rendering said imaging layer structurally fracturable by means of applying an activator to said imaging layer prior to its exposure said activator selected from the group consisting of partial solvents, solvents and swelling agents for said imaging layer and heat.

8. The method of claim 1 wherein said imaging layer comprises metal-free phthalocyanine in a binder.

9. The method of claim 1 wherein said imaging layer comprises metal-free phthalocyanine in a X crystalline form in a binder.

10. The method of claim 1 wherein said imaging layer comprises a mixture of photosensitive pigments in a binder.

11. The method of claim 1 wherein said imaging layer comprises a photosensitive composition in a binder said binder comprising an insulating resin composition.

12. The method of claim 1 wherein said imaging layer comprises a photosensitive composition in a binder said binder comprising a thermoplastic insulating composition.

13. A method of imaging comprising:

a. providing a manifold set comprising an imaging layer sandwiched between a donor sheet and a receiving sheet, said layer being structurally fracturable in response to the effect of an applied electric field;

b. maintaining an electric field across said imaging layer by means of a potential across said set;

0. modifying said electric potential in image configuration wherein said modification involves reducing, grounding or reversing said potential; and

d. separating said receiver sheet from said donor sheet whereby said imaging layer fractures in imagewise configuration forming a positive image on one of said donor and receiver sheets and a negative image on the other of said donor and receiving sheets and whereby the location of said images with respect to said donor and receiver sheets are reversed from those obtained in the above process in the absence of step (c).

14. A method of manifold layer transfer comprising:

a. providing a manifold set comprising an imaging layer sandwiched between a donor sheet and a receiving sheet, said layer being structurally fracturable in response to the effect of an applied electric field, said imaging layer having a stronger initial degree of adhesion for said donor sheet than for said receiving sheet;

b. maintaining an electric field across said imaging layer by means of a potential across said set;

c. modifying said electric potential across said set wherein said modification involves reducing, grounding or reversing said potential across said manifold set; and

d. separating said receiving sheet from said donor sheet whereby said imaging layer transfers to said receiver sheet as a result of said field modification.

15. The method of claim 14 wherein said imaging layer comprises dispersed organic photosensitive particles in a binder.

16. The method of claim 14 wherein said imaging layer comprises a photosensitive composition dispersed in a binder.

17. The method of claim 14 further including the step of rendering said imaging layer structurally fracturable by means of applying an activator to said layer said activator selected from the group consisting of partial solvents, solvents and swelling agents for said imaging layer and heat.

18. The method of claim 14 wherein said imaging layer comprises metal-free phthalocyanine in a binder.

nun

21. The method of claim 13 wherein said imaging layer comprises an organic photosensitive composition dispersed in a binder.

22. The method of claim 20 wherein said imaging layer comprises a non-photosensitive pigment dispersed in a binder.

23. The method of claim 13 wherein said electric field is in image configuration. 

2. The method of claim 1 wherein said modification comprises reducing said potential to a value less than one-third of the original potential, said modified potential being of the same polarity as said original potential.
 3. The method of claim 1 wherein said modification comprises grounding the potential across said manifold set.
 4. The method of claim 1 wherein said modification comprises reversing the polarity of said potential across said manifold set.
 5. The method of claim 1 wherein said donor sheet is at least partially transparent and said imaging layer is exposed through said donor sheet.
 6. The method of claim 1 wherein said receiver sheet is at least partially transparent and said imaging layer is exposed through said receiver sheet.
 7. The method of claim 1 further including the step of rendering said imaging layer structurally fracturable by means of applying an activator to said imaging layer prior to its exposure said activator selected from the group consisting of partial solvents, solvents and swelling agents for said imaging layer and heat.
 8. The method of claim 1 wherein said imaging layer comprises metal-free phthalocyanine in a binder.
 9. The method of claim 1 wherein said imaging layer comprises metal-free phthalocyanine in a X crystalline form in a binder.
 10. The method of claim 1 wherein said imaging layer comprises a mixture of photosensitive pigments in a binder.
 11. The method of claim 1 wherein said imaging layer comprises a photosensitive composition in a binder said binder comprising an insulating resin composition.
 12. The method of claim 1 wherein said imaging layer comprises a photosensitive composition in a binder said binder comprising a thermoplastic insulating composition.
 13. A method of imaging comprising: a. providing a manifold set comprising an imaging layer sandwiched between a donor sheet and a receiving sheet, said layer being structurally fracturable in response to the effect of an applied electric field; b. maintaining an electric field across said imaging layer by means of a potential across said set; c. modifying said electric potential in image configuration wherein said modification involves reducing, grounding or reversing said potential; and d. separating said receiver sheet from said donor sheet wheReby said imaging layer fractures in imagewise configuration forming a positive image on one of said donor and receiver sheets and a negative image on the other of said donor and receiving sheets and whereby the location of said images with respect to said donor and receiver sheets are reversed from those obtained in the above process in the absence of step (c).
 14. A method of manifold layer transfer comprising: a. providing a manifold set comprising an imaging layer sandwiched between a donor sheet and a receiving sheet, said layer being structurally fracturable in response to the effect of an applied electric field, said imaging layer having a stronger initial degree of adhesion for said donor sheet than for said receiving sheet; b. maintaining an electric field across said imaging layer by means of a potential across said set; c. modifying said electric potential across said set wherein said modification involves reducing, grounding or reversing said potential across said manifold set; and d. separating said receiving sheet from said donor sheet whereby said imaging layer transfers to said receiver sheet as a result of said field modification.
 15. The method of claim 14 wherein said imaging layer comprises dispersed organic photosensitive particles in a binder.
 16. The method of claim 14 wherein said imaging layer comprises a photosensitive composition dispersed in a binder.
 17. The method of claim 14 further including the step of rendering said imaging layer structurally fracturable by means of applying an activator to said layer said activator selected from the group consisting of partial solvents, solvents and swelling agents for said imaging layer and heat.
 18. The method of claim 14 wherein said imaging layer comprises metal-free phthalocyanine in a binder.
 19. The method of claim 14 wherein said imaging layer comprises the X crystalline form of metal-free phthalocyanine in a binder.
 20. The method of claim 13 further including the steps of rendering said layer structurally fracturable by means of applying an activator to said imaging layer prior to modifying said electric field in image configuration said activator selected from the group consisting of solvents, partial solvents and swelling agents for said imaging layer and heat.
 21. The method of claim 13 wherein said imaging layer comprises an organic photosensitive composition dispersed in a binder.
 22. The method of claim 20 wherein said imaging layer comprises a non-photosensitive pigment dispersed in a binder.
 23. The method of claim 13 wherein said electric field is in image configuration. 